Must admit I've been looking for something along those lines as your generic rotating beacon with a rather power hungry 55w halogen lamp wasnt an option, well unless you wanted to lug a huge lead acid battery around I opted for a pile of these MegaFlares in yellow.

Managed to pick up a job lot of 10 for about £20 from flea bay, they run on single use Li-ion batteries but you can fit standard 18350 rechargables in to them, they are light weight, magnetic and so you dont need any real heavy weight poles and fixings